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/*
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 * Copyright (c) 2007-2012, Stephen Colebourne & Michael Nascimento Santos
 *
 * All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
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package java.time.chrono;

import static java.time.temporal.ChronoField.EPOCH_DAY;
import static java.time.temporal.ChronoField.NANO_OF_DAY;
import static java.time.temporal.ChronoUnit.FOREVER;
import static java.time.temporal.ChronoUnit.NANOS;

import java.time.DateTimeException;
import java.time.Instant;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.ZoneId;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;
import java.time.temporal.ChronoField;
import java.time.temporal.ChronoUnit;
import java.time.temporal.Temporal;
import java.time.temporal.TemporalAccessor;
import java.time.temporal.TemporalAdjuster;
import java.time.temporal.TemporalAmount;
import java.time.temporal.TemporalField;
import java.time.temporal.TemporalQueries;
import java.time.temporal.TemporalQuery;
import java.time.temporal.TemporalUnit;
import java.time.zone.ZoneRules;
import java.util.Comparator;
import java.util.Objects;

/**
 * A date-time without a time-zone in an arbitrary chronology, intended
 * for advanced globalization use cases.
 * <p>
 * <b>Most applications should declare method signatures, fields and variables
 * as {@link LocalDateTime}, not this interface.</b>
 * <p>
 * A {@code ChronoLocalDateTime} is the abstract representation of a local date-time
 * where the {@code Chronology chronology}, or calendar system, is pluggable.
 * The date-time is defined in terms of fields expressed by {@link TemporalField},
 * where most common implementations are defined in {@link ChronoField}.
 * The chronology defines how the calendar system operates and the meaning of
 * the standard fields.
 *
 * <h3>When to use this interface</h3>
 * The design of the API encourages the use of {@code LocalDateTime} rather than this
 * interface, even in the case where the application needs to deal with multiple
 * calendar systems. The rationale for this is explored in detail in {@link ChronoLocalDate}.
 * <p>
 * Ensure that the discussion in {@code ChronoLocalDate} has been read and understood
 * before using this interface.
 *
 * @param <D> the concrete type for the date of this date-time
 * @implSpec This interface must be implemented with care to ensure other classes operate correctly.
 * All implementations that can be instantiated must be final, immutable and thread-safe. Subclasses
 * should be Serializable wherever possible.
 * @since 1.8
 */
public interface ChronoLocalDateTime<D extends ChronoLocalDate>
    extends Temporal, TemporalAdjuster, Comparable<ChronoLocalDateTime<?>> {

  /**
   * Gets a comparator that compares {@code ChronoLocalDateTime} in
   * time-line order ignoring the chronology.
   * <p>
   * This comparator differs from the comparison in {@link #compareTo} in that it
   * only compares the underlying date-time and not the chronology.
   * This allows dates in different calendar systems to be compared based
   * on the position of the date-time on the local time-line.
   * The underlying comparison is equivalent to comparing the epoch-day and nano-of-day.
   *
   * @return a comparator that compares in time-line order ignoring the chronology
   * @see #isAfter
   * @see #isBefore
   * @see #isEqual
   */
  static Comparator<ChronoLocalDateTime<?>> timeLineOrder() {
    return AbstractChronology.DATE_TIME_ORDER;
  }

  //-----------------------------------------------------------------------

  /**
   * Obtains an instance of {@code ChronoLocalDateTime} from a temporal object.
   * <p>
   * This obtains a local date-time based on the specified temporal.
   * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
   * which this factory converts to an instance of {@code ChronoLocalDateTime}.
   * <p>
   * The conversion extracts and combines the chronology and the date-time
   * from the temporal object. The behavior is equivalent to using
   * {@link Chronology#localDateTime(TemporalAccessor)} with the extracted chronology.
   * Implementations are permitted to perform optimizations such as accessing
   * those fields that are equivalent to the relevant objects.
   * <p>
   * This method matches the signature of the functional interface {@link TemporalQuery}
   * allowing it to be used as a query via method reference, {@code ChronoLocalDateTime::from}.
   *
   * @param temporal the temporal object to convert, not null
   * @return the date-time, not null
   * @throws DateTimeException if unable to convert to a {@code ChronoLocalDateTime}
   * @see Chronology#localDateTime(TemporalAccessor)
   */
  static ChronoLocalDateTime<?> from(TemporalAccessor temporal) {
    if (temporal instanceof ChronoLocalDateTime) {
      return (ChronoLocalDateTime<?>) temporal;
    }
    Objects.requireNonNull(temporal, "temporal");
    Chronology chrono = temporal.query(TemporalQueries.chronology());
    if (chrono == null) {
      throw new DateTimeException(
          "Unable to obtain ChronoLocalDateTime from TemporalAccessor: " + temporal.getClass());
    }
    return chrono.localDateTime(temporal);
  }

  //-----------------------------------------------------------------------

  /**
   * Gets the chronology of this date-time.
   * <p>
   * The {@code Chronology} represents the calendar system in use.
   * The era and other fields in {@link ChronoField} are defined by the chronology.
   *
   * @return the chronology, not null
   */
  default Chronology getChronology() {
    return toLocalDate().getChronology();
  }

  /**
   * Gets the local date part of this date-time.
   * <p>
   * This returns a local date with the same year, month and day
   * as this date-time.
   *
   * @return the date part of this date-time, not null
   */
  D toLocalDate();

  /**
   * Gets the local time part of this date-time.
   * <p>
   * This returns a local time with the same hour, minute, second and
   * nanosecond as this date-time.
   *
   * @return the time part of this date-time, not null
   */
  LocalTime toLocalTime();

  /**
   * Checks if the specified field is supported.
   * <p>
   * This checks if the specified field can be queried on this date-time.
   * If false, then calling the {@link #range(TemporalField) range},
   * {@link #get(TemporalField) get} and {@link #with(TemporalField, long)}
   * methods will throw an exception.
   * <p>
   * The set of supported fields is defined by the chronology and normally includes
   * all {@code ChronoField} date and time fields.
   * <p>
   * If the field is not a {@code ChronoField}, then the result of this method
   * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
   * passing {@code this} as the argument.
   * Whether the field is supported is determined by the field.
   *
   * @param field the field to check, null returns false
   * @return true if the field can be queried, false if not
   */
  @Override
  boolean isSupported(TemporalField field);

  /**
   * Checks if the specified unit is supported.
   * <p>
   * This checks if the specified unit can be added to or subtracted from this date-time.
   * If false, then calling the {@link #plus(long, TemporalUnit)} and
   * {@link #minus(long, TemporalUnit) minus} methods will throw an exception.
   * <p>
   * The set of supported units is defined by the chronology and normally includes
   * all {@code ChronoUnit} units except {@code FOREVER}.
   * <p>
   * If the unit is not a {@code ChronoUnit}, then the result of this method
   * is obtained by invoking {@code TemporalUnit.isSupportedBy(Temporal)}
   * passing {@code this} as the argument.
   * Whether the unit is supported is determined by the unit.
   *
   * @param unit the unit to check, null returns false
   * @return true if the unit can be added/subtracted, false if not
   */
  @Override
  default boolean isSupported(TemporalUnit unit) {
    if (unit instanceof ChronoUnit) {
      return unit != FOREVER;
    }
    return unit != null && unit.isSupportedBy(this);
  }

  //-----------------------------------------------------------------------
  // override for covariant return type

  /**
   * {@inheritDoc}
   *
   * @throws DateTimeException {@inheritDoc}
   * @throws ArithmeticException {@inheritDoc}
   */
  @Override
  default ChronoLocalDateTime<D> with(TemporalAdjuster adjuster) {
    return ChronoLocalDateTimeImpl.ensureValid(getChronology(), Temporal.super.with(adjuster));
  }

  /**
   * {@inheritDoc}
   *
   * @throws DateTimeException {@inheritDoc}
   * @throws ArithmeticException {@inheritDoc}
   */
  @Override
  ChronoLocalDateTime<D> with(TemporalField field, long newValue);

  /**
   * {@inheritDoc}
   *
   * @throws DateTimeException {@inheritDoc}
   * @throws ArithmeticException {@inheritDoc}
   */
  @Override
  default ChronoLocalDateTime<D> plus(TemporalAmount amount) {
    return ChronoLocalDateTimeImpl.ensureValid(getChronology(), Temporal.super.plus(amount));
  }

  /**
   * {@inheritDoc}
   *
   * @throws DateTimeException {@inheritDoc}
   * @throws ArithmeticException {@inheritDoc}
   */
  @Override
  ChronoLocalDateTime<D> plus(long amountToAdd, TemporalUnit unit);

  /**
   * {@inheritDoc}
   *
   * @throws DateTimeException {@inheritDoc}
   * @throws ArithmeticException {@inheritDoc}
   */
  @Override
  default ChronoLocalDateTime<D> minus(TemporalAmount amount) {
    return ChronoLocalDateTimeImpl.ensureValid(getChronology(), Temporal.super.minus(amount));
  }

  /**
   * {@inheritDoc}
   *
   * @throws DateTimeException {@inheritDoc}
   * @throws ArithmeticException {@inheritDoc}
   */
  @Override
  default ChronoLocalDateTime<D> minus(long amountToSubtract, TemporalUnit unit) {
    return ChronoLocalDateTimeImpl
        .ensureValid(getChronology(), Temporal.super.minus(amountToSubtract, unit));
  }

  //-----------------------------------------------------------------------

  /**
   * Queries this date-time using the specified query.
   * <p>
   * This queries this date-time using the specified query strategy object.
   * The {@code TemporalQuery} object defines the logic to be used to
   * obtain the result. Read the documentation of the query to understand
   * what the result of this method will be.
   * <p>
   * The result of this method is obtained by invoking the
   * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
   * specified query passing {@code this} as the argument.
   *
   * @param <R> the type of the result
   * @param query the query to invoke, not null
   * @return the query result, null may be returned (defined by the query)
   * @throws DateTimeException if unable to query (defined by the query)
   * @throws ArithmeticException if numeric overflow occurs (defined by the query)
   */
  @SuppressWarnings("unchecked")
  @Override
  default <R> R query(TemporalQuery<R> query) {
    if (query == TemporalQueries.zoneId() || query == TemporalQueries.zone()
        || query == TemporalQueries.offset()) {
      return null;
    } else if (query == TemporalQueries.localTime()) {
      return (R) toLocalTime();
    } else if (query == TemporalQueries.chronology()) {
      return (R) getChronology();
    } else if (query == TemporalQueries.precision()) {
      return (R) NANOS;
    }
    // inline TemporalAccessor.super.query(query) as an optimization
    // non-JDK classes are not permitted to make this optimization
    return query.queryFrom(this);
  }

  /**
   * Adjusts the specified temporal object to have the same date and time as this object.
   * <p>
   * This returns a temporal object of the same observable type as the input
   * with the date and time changed to be the same as this.
   * <p>
   * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
   * twice, passing {@link ChronoField#EPOCH_DAY} and
   * {@link ChronoField#NANO_OF_DAY} as the fields.
   * <p>
   * In most cases, it is clearer to reverse the calling pattern by using
   * {@link Temporal#with(TemporalAdjuster)}:
   * <pre>
   *   // these two lines are equivalent, but the second approach is recommended
   *   temporal = thisLocalDateTime.adjustInto(temporal);
   *   temporal = temporal.with(thisLocalDateTime);
   * </pre>
   * <p>
   * This instance is immutable and unaffected by this method call.
   *
   * @param temporal the target object to be adjusted, not null
   * @return the adjusted object, not null
   * @throws DateTimeException if unable to make the adjustment
   * @throws ArithmeticException if numeric overflow occurs
   */
  @Override
  default Temporal adjustInto(Temporal temporal) {
    return temporal
        .with(EPOCH_DAY, toLocalDate().toEpochDay())
        .with(NANO_OF_DAY, toLocalTime().toNanoOfDay());
  }

  /**
   * Formats this date-time using the specified formatter.
   * <p>
   * This date-time will be passed to the formatter to produce a string.
   * <p>
   * The default implementation must behave as follows:
   * <pre>
   *  return formatter.format(this);
   * </pre>
   *
   * @param formatter the formatter to use, not null
   * @return the formatted date-time string, not null
   * @throws DateTimeException if an error occurs during printing
   */
  default String format(DateTimeFormatter formatter) {
    Objects.requireNonNull(formatter, "formatter");
    return formatter.format(this);
  }

  //-----------------------------------------------------------------------

  /**
   * Combines this time with a time-zone to create a {@code ChronoZonedDateTime}.
   * <p>
   * This returns a {@code ChronoZonedDateTime} formed from this date-time at the
   * specified time-zone. The result will match this date-time as closely as possible.
   * Time-zone rules, such as daylight savings, mean that not every local date-time
   * is valid for the specified zone, thus the local date-time may be adjusted.
   * <p>
   * The local date-time is resolved to a single instant on the time-line.
   * This is achieved by finding a valid offset from UTC/Greenwich for the local
   * date-time as defined by the {@link ZoneRules rules} of the zone ID.
   * <p>
   * In most cases, there is only one valid offset for a local date-time.
   * In the case of an overlap, where clocks are set back, there are two valid offsets.
   * This method uses the earlier offset typically corresponding to "summer".
   * <p>
   * In the case of a gap, where clocks jump forward, there is no valid offset.
   * Instead, the local date-time is adjusted to be later by the length of the gap.
   * For a typical one hour daylight savings change, the local date-time will be
   * moved one hour later into the offset typically corresponding to "summer".
   * <p>
   * To obtain the later offset during an overlap, call
   * {@link ChronoZonedDateTime#withLaterOffsetAtOverlap()} on the result of this method.
   *
   * @param zone the time-zone to use, not null
   * @return the zoned date-time formed from this date-time, not null
   */
  ChronoZonedDateTime<D> atZone(ZoneId zone);

  //-----------------------------------------------------------------------

  /**
   * Converts this date-time to an {@code Instant}.
   * <p>
   * This combines this local date-time and the specified offset to form
   * an {@code Instant}.
   * <p>
   * This default implementation calculates from the epoch-day of the date and the
   * second-of-day of the time.
   *
   * @param offset the offset to use for the conversion, not null
   * @return an {@code Instant} representing the same instant, not null
   */
  default Instant toInstant(ZoneOffset offset) {
    return Instant.ofEpochSecond(toEpochSecond(offset), toLocalTime().getNano());
  }

  /**
   * Converts this date-time to the number of seconds from the epoch
   * of 1970-01-01T00:00:00Z.
   * <p>
   * This combines this local date-time and the specified offset to calculate the
   * epoch-second value, which is the number of elapsed seconds from 1970-01-01T00:00:00Z.
   * Instants on the time-line after the epoch are positive, earlier are negative.
   * <p>
   * This default implementation calculates from the epoch-day of the date and the
   * second-of-day of the time.
   *
   * @param offset the offset to use for the conversion, not null
   * @return the number of seconds from the epoch of 1970-01-01T00:00:00Z
   */
  default long toEpochSecond(ZoneOffset offset) {
    Objects.requireNonNull(offset, "offset");
    long epochDay = toLocalDate().toEpochDay();
    long secs = epochDay * 86400 + toLocalTime().toSecondOfDay();
    secs -= offset.getTotalSeconds();
    return secs;
  }

  //-----------------------------------------------------------------------

  /**
   * Compares this date-time to another date-time, including the chronology. <p> The comparison is
   * based first on the underlying time-line date-time, then on the chronology. It is "consistent
   * with equals", as defined by {@link Comparable}. <p> For example, the following is the
   * comparator order: <ol> <li>{@code 2012-12-03T12:00 (ISO)}</li> <li>{@code 2012-12-04T12:00
   * (ISO)}</li> <li>{@code 2555-12-04T12:00 (ThaiBuddhist)}</li> <li>{@code 2012-12-05T12:00
   * (ISO)}</li> </ol> Values #2 and #3 represent the same date-time on the time-line. When two
   * values represent the same date-time, the chronology ID is compared to distinguish them. This
   * step is needed to make the ordering "consistent with equals". <p> If all the date-time objects
   * being compared are in the same chronology, then the additional chronology stage is not required
   * and only the local date-time is used. <p> This default implementation performs the comparison
   * defined above.
   *
   * @param other the other date-time to compare to, not null
   * @return the comparator value, negative if less, positive if greater
   */
  @Override
  default int compareTo(ChronoLocalDateTime<?> other) {
    int cmp = toLocalDate().compareTo(other.toLocalDate());
    if (cmp == 0) {
      cmp = toLocalTime().compareTo(other.toLocalTime());
      if (cmp == 0) {
        cmp = getChronology().compareTo(other.getChronology());
      }
    }
    return cmp;
  }

  /**
   * Checks if this date-time is after the specified date-time ignoring the chronology.
   * <p>
   * This method differs from the comparison in {@link #compareTo} in that it
   * only compares the underlying date-time and not the chronology.
   * This allows dates in different calendar systems to be compared based
   * on the time-line position.
   * <p>
   * This default implementation performs the comparison based on the epoch-day
   * and nano-of-day.
   *
   * @param other the other date-time to compare to, not null
   * @return true if this is after the specified date-time
   */
  default boolean isAfter(ChronoLocalDateTime<?> other) {
    long thisEpDay = this.toLocalDate().toEpochDay();
    long otherEpDay = other.toLocalDate().toEpochDay();
    return thisEpDay > otherEpDay ||
        (thisEpDay == otherEpDay && this.toLocalTime().toNanoOfDay() > other.toLocalTime()
            .toNanoOfDay());
  }

  /**
   * Checks if this date-time is before the specified date-time ignoring the chronology.
   * <p>
   * This method differs from the comparison in {@link #compareTo} in that it
   * only compares the underlying date-time and not the chronology.
   * This allows dates in different calendar systems to be compared based
   * on the time-line position.
   * <p>
   * This default implementation performs the comparison based on the epoch-day
   * and nano-of-day.
   *
   * @param other the other date-time to compare to, not null
   * @return true if this is before the specified date-time
   */
  default boolean isBefore(ChronoLocalDateTime<?> other) {
    long thisEpDay = this.toLocalDate().toEpochDay();
    long otherEpDay = other.toLocalDate().toEpochDay();
    return thisEpDay < otherEpDay ||
        (thisEpDay == otherEpDay && this.toLocalTime().toNanoOfDay() < other.toLocalTime()
            .toNanoOfDay());
  }

  /**
   * Checks if this date-time is equal to the specified date-time ignoring the chronology.
   * <p>
   * This method differs from the comparison in {@link #compareTo} in that it
   * only compares the underlying date and time and not the chronology.
   * This allows date-times in different calendar systems to be compared based
   * on the time-line position.
   * <p>
   * This default implementation performs the comparison based on the epoch-day
   * and nano-of-day.
   *
   * @param other the other date-time to compare to, not null
   * @return true if the underlying date-time is equal to the specified date-time on the timeline
   */
  default boolean isEqual(ChronoLocalDateTime<?> other) {
    // Do the time check first, it is cheaper than computing EPOCH day.
    return this.toLocalTime().toNanoOfDay() == other.toLocalTime().toNanoOfDay() &&
        this.toLocalDate().toEpochDay() == other.toLocalDate().toEpochDay();
  }

  /**
   * Checks if this date-time is equal to another date-time, including the chronology.
   * <p>
   * Compares this date-time with another ensuring that the date-time and chronology are the same.
   *
   * @param obj the object to check, null returns false
   * @return true if this is equal to the other date
   */
  @Override
  boolean equals(Object obj);

  /**
   * A hash code for this date-time.
   *
   * @return a suitable hash code
   */
  @Override
  int hashCode();

  //-----------------------------------------------------------------------

  /**
   * Outputs this date-time as a {@code String}.
   * <p>
   * The output will include the full local date-time.
   *
   * @return a string representation of this date-time, not null
   */
  @Override
  String toString();

}
